Police block off a section of Yogananda Street on Friday near a house belonging Adam Lanza's mother. / Jason DeCrow, AP

by By Donna Leinwand Leger, Gary Stoller and Gary Strauss

by By Donna Leinwand Leger, Gary Stoller and Gary Strauss

NEWTOWN, Conn. -- In the aftermath of one of the worst school massacres in U.S history, authorities are trying to piece together a profile of Adam Lanza and what drove the 20-year-old to kill his mother Friday morning, then shoot his way into Sandy Hook Elementary School and execute 26 students and faculty before taking his own life.

As many in this bucolic town of 27,000 were grieving and grappling for answers and much of the nation mourned, authorities were still searching for a motive. Law enforcement officials say Lanza suffered from a personality order.

Some news media reports say Lanza had a confrontation with someone at the school days ahead of the shooting spree, but authorities said Saturday that they had no information to confirm that and that they had found no suicide notes or manifesto.

Family and friends say Lanza was many things -- intelligent, nerdy, goth, remote, thin. He did not appear to have a job and had no criminal record.

However, dressed in military-style gear Friday, Lanza appeared to be on a mission of death. Authorities say he killed his mother, Nancy Lanza, at her Newtown home, then drove to Sandy Hook Elementary School, where they say he shot his way into the building before methodically shooting 20 students and six faculty members several times and taking his own life. The state's chief medical examiner, H. Wayne Carver II, said Saturday that some of the victims had up to 11 bullet wounds.

For at least part of their education, Nancy Lanza home schooled both Adam and older brother Ryan, 24, who attended and graduated from Newtown High. Adam attended the local high school for just a few months, said Louise Tambascio, owner of My Place, an Italian restaurant in Newtown that Nancy Lanza frequented. Tambascio had known Nancy for 12 years. She had visited the family's home and described it as "beautiful, gorgeous" and well kept.

At least three of the weapons used in the shootings were owned and registered to Nancy Lanza. More weapons have been found at the home. Tambascio described Nancy Lanza's collection of guns as "a hobby."

Neighbors said Saturday they were puzzled that so few of them knew the Lanzas.

"We walked by their house with the dog every day, and we don't know them," said Dave Lapp. " We've never even seen them and they are literally around the corner." .

A Newtown High School yearbook from 2008 lists Adam Lanza as a member of the sophomore class, but his school portrait doesn't appear. He didn't attend Sandy Hook Elementary, Tambascio said.

"It's just so horrific. I never thought he would do anything like that," she said. "I don't know why he (targeted Sandy Hook.) He never even went there. "

Ryan Lanza worked at the restaurant for two years busing tables, she said. "Ryan was the complete opposite of his brother," she said. The brothers haven't spoken in two years. "It got to be too much for Ryan," Tambascio said.

Nancy Lanza had trouble with her younger son for years, Tambascio said. He was diagnosed with a type of autism known as Asperger syndrome, she said.

"He always had his face down. He would never look you In the eye," she said. "She's always had problems with him, since he was young."

One of Lanza's middle school classmates at Newtown Middle School, who requested anonymity, described him as smart, but odd, more animated and less social than other students.

News clippings show that Adam was an honor roll student while at Newtown High. Joshua Milas, a classmate who was in the technology club with him, said that he was generally a happy person but that he hadn't seen him in a few years.

"We would hang out, and he was a good kid. He was smart," said Milas, who graduated in 2009. "He was probably one of the smartest kids I know. He was probably a genius."

The tech club held parties at members' homes, hooking up their computers to play games. Gloria Milas, Joshua's mother, hosted one of the parties. She recalled a 2008 school meeting organized by Nancy Lanza to try to save the job of the club's adviser. At the meeting, Milas said, Ryan Lanza said a few words in support of the adviser, who he said had taken his brother under his wing.

"My brother has always been a nerd," Ryan Lanza said then, according to Milas. "He still wears a pocket protector."

Catherine Urso, who attended a vigil Friday evening in Newtown, Conn., said her college-age son knew Ryan Lanza and remembered him for his alternative style.

"He just said he was very thin, very remote and was one of the goths," referring to a style of dress noted for a heavily black wardrobe.

Nancy and husband Peter Lanza filed for divorce in 2008. They were divorced in 2009 after 28 years of marriage because of "irreconcilable differences,'' according to court records. Peter Lanza is a vice president for taxes of GE Energy Financial Services. Adam was 17 at the time of the divorce.

His aunt Marsha Lanza of Crystal Lake, Ill., said her nephew was raised by kind, nurturing parents who would not have hesitated to seek mental help for him if he needed it.

If her son had needed counseling, "Nancy wasn't one to deny reality," she said.

Lanza said she was close with Nancy Lanza and had sent her a Facebook message Friday morning asking how she was doing. Nancy Lanza never responded.

Nancy Lanza's mother was too distraught to speak when reached by phone at her home in Brooksville, Fla.

"I just don't know, and I can't make a comment right now," Dorothy Hanson, 78, said.